Todd Brown, MD, PhD, an Associate Professor of Medicine and Endocrinology in the Division of Endocrinology, Diabetes, & Metabolism at Johns Hopkins University, submits this application for a K24 Mid-Career Development award to provide protected time to mentor trainees in patient- oriented research in HIV Endocrinology. Dr. Brown is one of the few endocrinologists worldwide specializing in endocrine and metabolic disorders in HIV-infected patients. He will pursue additional training to hone his mentoring skills in order to build on his established record of mentorship and foster the research careers of early investigators. Candidate: Dr. Brown is a highly productive clinical researcher in the HIV Comorbidities field. Since 2004, he has been continuously NIH-funded to investigate the epidemiology, pathogenesis, and clinical management of endocrine and metabolic dysfunction in HIV-infected persons, using long-standing, NIH-supported infrastructure as a platform for his investigations, including the Multicenter AIDS Cohort Study (MACS), the Women's Interagency HIV Study (WIHS), and the AIDS Clinical Trials Group. With his uncommon skill set and strong POR program in endocrine and metabolic complications in HIV, he has been a sought-after collaborator and mentor at Johns Hopkins and at institutions from around the country. Mentoring Plan/Environment: This application will leverage the extensive training resources at Johns Hopkins, including the Center for AIDS Research, the Institute for Clinical and Translational Research, and T32 training grants in a variety of specialties. It will also draw on the unparallele resources of the MACS and WIHS and other funded studies to serve as a platform for POR trainees at multiple levels. Research Plan: The novel research supported by this K24 award will make a significant contribution to the understanding of the causes and consequences of endocrine and metabolic abnormalities in HIV-infected persons in three major areas: 1) Osteoporosis and Fracture Risk, 2) Hypogonadism, and 3) Insulin Resistance. It will build on ongoing work in the MACS and WIHS, explore new hypotheses, and expand opportunities for trainees.